CLOSURE FOR A CABLE JOINT

Abstract: A closure for a cable joint, comprising a lid portion (1) and a body portion (2) arranged to be fastened together substantially to close the closure, sealing means (3) for sealing the interior of the closure against ingress of moisture, wherein the sealing means (3) is locted between the lid portion (1) and the body portion (2) when the two portions are fastened together in use, and wherein the lid portion (1) and/or the body portion (2) is/are provided with flap means (4) which when the two portions are fastened together in use is located to the exterior of the closure in relation to the sealing means (3) and is arranged substantially to block ingress of dirt of the like between the lid and body portions while allowing some convergence and/or divergence of the lid and body portions when they are fastened together in use.

Description: CLOSURE FORACABLEJOINT The present invention relates to closures for cable joints, particularly closures comprising a lid portion and a body portion. Closures for cable joints which have the form of a hollow body portion and a lid which may be opened to allow access to the closure are known. For example, WR151 PCT [soon to be published] discloses a sleeve having a base body part and a cover body part in the form of a lid that is pivoted with respect to the base. The lid may be fastened closed by means of a clamping rail or a clamping screw for example, and the closure is sealed by means of a seal interposed between the walls of the base body and the lid. Cable joint closures are normally required to remain closed and sealed for long periods of time, and during this time the closures often experience relatively severe temperature fluctuations. One advantage of closures which have the form of a body portion and a lid is that they may be opened and re- closed as often as necessary during their operational lifetime, generally without disturbing seals to ingoing cables. It is therefore a requirement of such closures that they remain sealed despite experiencing temperature fluctuations and that they may be reliably re-sealed, once opened, as often as necessary. According to the invention, there is provided a closure for a cable joint, comprising a lid portion and a body portion arranged to be fastened together substantially to close the closure, sealing means (such as a strip of sealing material, running for example around the perimeter of body and/or lid) for sealing the interior of the closure against ingress of moisture, wherein the sealing means is located between the lid portion and the body portion when the two portions are fastened together in use, and wherein the lid portion and/or the body portion is /are provided with flap means which when the two portions are fastened together in use is located to the exterior of the closure in relation to the sealing means and is arranged substantially to block ingress of dirt or the like between the lid and body portions while allowing some convergence and/or divergence of the lid and body portions when they are fastened together in use. The sealing means preferably provides a seal between body and lid when body and lid are spaced a significant distance, such as 0.1 - 5 mm, apart thus allowing relative movement. This can be compared with an adhesive bond of insignificant thickness that would be irreparably broken by any relative movement between body and lid. We prefer that movement between body and lid be accommodated by resilience or other deformability of the sealing material or other sealing means. Such sealing material etc should therefore be able to wet the surface of the body and/or lid (or otherwise form a seal) and also be able to store energy when the closure is closed. Subsequent relaxation allows a seal to be maintained on body and lid diverge. A sealing material can be chosen that comprises two components (such as two layers) one of which form a seal and the other of which stores energy. This can be achieved, for example, by means of a gel or mastic or elastomer. An example of suitable material is a lightly cross-linked silicone or other rubber; different layers of different cross-link densities can be used to form the two components referred to. In order to ensure that closures of the type having a body portion and a lid portion are sealed from the environment, it is therefore normally necessary to provide a seal between the lid and the body. A problem associated with such an arrangement (especially when a significant gap is provided as mentioned above) is that, during the operational life of the closure, dirt, dust, grit or the like often becomes trapped between the lid and the body, (to the exterior of the seal) due to this gap, between the lid and the body. We have found that this gap between the lid and the body is, in fact, desirable since it allows the seal to contract as a result of a change in temperature, for example an increase in the temperature, without the environmental seal being broken. However, if dirt or other foreign matter is allowed to lodge in the gap between the lid and the body, when the seal contracts as a result of a temperature change, the lid and the body will not be able to converge in order to maintain the environmental seal between them and consequently moisture will be able to enter the closure. In addition, the presence of dirt or the like between the lid and the body may prevent a satisfactory seal being re-formed once the closure has been opened. The present invention solves the above problem since it substantially prevents the ingress of dirt or the like between the lid and body portions of a closure, while allowing the two portions to converge and/or diverge, for example as a result of temperature fluctuations, and therefore helps to maintain the closure environmentally sealed. Preferably the invention acts substantially to block ingress of dirt when the body and lid at substantially all relative positions thereof arising during service life of the closed closure , and also during relative movement. Alternative attempts to achieve the benefits of the present invention have failed because they have not allowed the lid and body portions to converge and diverge, due for example, to thermal cycling or to mechanical stresses, throughout the operational lifetime of the closure. For example, the provision of a resiliently compressible foam block between the lid and body portions to the exterior of the seal might initially prevent ingress of dirt while allowing convergence and divergence of the lid and body. However, over a period of time foam normally tends to harden until it is no longer resiliently compressible, and it therefore either no longer prevents ingress of dirt or no longer allows convergence and divergence of the lid and body, and in either case the environmental seal eventually fails. UK Patent No. 1506748 discloses an enclosure for a cable joint comprising a sleeve having a single axially-directed slit, a plastic sealing mass located between opposite edges of the slit, and a clamping bar which cooperates with flanges extruding outwardly from the slit, for clamping the sleeve closed. One type of sleeve disclosed in GB 1506748 has a projection on the inside of the sleeve, which overlaps the slit in the sleeve and is sealed to the opposing part of the inside of the sleeve in this overlapping configuration. This type of sleeve is used for cable joints under an internal gas pressure since the projection helps to maintain the internal pressure in the sleeve. An alternative type of sleeve disclosed in GB 1506748 is formed with a groove along the inside of one of the opposing edges of the slit in the sleeve and with a mating projection on the other opposing edge of the sleeve. This arrangement helps uniformly to distribute a plastic sealing mass inserted into the groove, thereby providing a reliable seal for the sleeve. GB 1506748 therefore describes the use of projections to aid the sealing of a cable enclosure in the form of a slit sleeve, but it does not describe or suggest the use of flap means to block ingress of dirt or the like into the sleeve and does not describe a body and lid at all, nor of course, the resulting problem of opening/closing etc due to thermal or mechanical loads acting on substantially rigid bodies and lids. Also, a clamping member is fixed across the slit of GB 1506748 and that prevents ingress of dirt into the slit but does not allow movement. A sleeve is of substantially uniform construction around its circumference and as a result any stresses can be more easily accommodated since deformation can be spread around the circumferences. The flap means according to the present invention may have any of a variety of forms. For example, the flap means may be substantially rigid, or it may be flexible, e.g. resiliently flexible, depending on the particular design and requirements of the closure The resilience may cause a flap attached to the lid to be biased against the body or vice versa, in such a way that relative motion (preferably predominantly sliding motion) is allowed. This motion may be achieved with minimal bending or other deformation of the flap, thus prolonging its lifetime. The flap means may comprise one or more flaps as such which may, for example, overlap or interlock in a variety of ways, or the flap means may comprise one or more ledges, shoulders and/or recesses in the lid and/or body portions of the closure. One or more flaps may extend around all or part of the perimeter of the closure. In a preferred embodiment of the invention, the flap means of the closure comprises a flap provided on the exterior of one of the portions (i.e. lid or body portions) of the closure, and is arranged to overlap part of the exterior of the other portion of the closure when the two portions are fastened together in use. This has the advantage of simplicity and therefore this preferred embodiment will normally be relatively simple and inexpensive to manufacture. In a particularly preferred embodiment, the flap is provided on the lid portion of the closure. This embodiment is advantageous because normally the lid portion of the closure will be above the body portion in use, and therefore dirt and debris falling on to or pressing down on the closure will not easily become lodged between the flap and the exterior of the closure and consequently will not be able to lodge between the lid and body portions, or to force the flap away from the body. The lid and body portions of the closure according to the invention may have any of a variety of forms. For example, the lid may comprise a relatively flat portion which is arranged to close a body portion in the form of a box, for example a substantially rectangular box. Alternatively, both the lid and body portions may have similar shapes, for example they may comprise the two halves of a closure. The closure may additionally comprise further portions which may or may not be separable, for example the closure may, if desired, comprise a body portion which forms the major part of the closure and which may be closed off by means of two lid portions arranged to be fastened to opposing sides of the body portion. Depending upon the particular requirements of the cable closure, it will have one or more cable entry ports, for example apertures or slots, arranged in the desired manner. A preferred form of closure according to the invention is one arranged for in-line splices, for example for telecommunications cables, which has cable entry ports provided at opposite ends of the closure. The cables may be sealed at the join line between body and lid, so each contributes to sealing, but this has the disadvantage that opening of the lid will break the seals to the cables. Thus, it may be desirable if the cables and sealed wholly within one of the body and lid (optionally with one or more ancillary components). The present invention is particularly applicable to cable closures in which the lid portion and the body portion are pivoted with respect to each other, for example hinged together. By "pivoted" we include connections with allow both pivoted and translational movement between the body and lid. Translational movement might be desirable as the body and lid finally move together in order that any seal between them be not deformed as the closure is closed. The lid portion and the body portion of the closure may be fastened together in any of a variety of ways. Preferably the closure is provided with one or more clamping elements for fastening the lid and body portions together. Each clamping element preferably has a longitudinal channel that has recessed side-walls and is arranged to be slid on to cooperating flanges on the lid and body portions of the closure. More preferably, the longitudinal channel of each clamping element is also substantially wedge-shaped and is arranged to be slid on to correspondingly wedge-shaped flanges on the lid and body portions so that the two portions become more tightly fastened together as the clamping element is pushed along the flanges. The invention will now be described, by way of example, with reference to the accompanying drawings, in which : Figure 1 , shows a first embodiment of the invention; Figure 2A and 2B, show a second embodiments of the invention; and Figure 3, shows a cable splice case embodying the invention. Figure 1 shows a sealing means (3) located between a lid and portion (1) and a body portion (2) of a cable splice case. The lid portion (1) carries a flap means (4) which can be seen to block a gap between the lid means (1) and the body means (2) but which can allow some convergency and/or divergence between them. In this way sealing means (3) is protected from ingress of dirt or the like between the lid and body portions allowing it to retain its sealing properties during service life of the splice closure, even after re-entry. The lid portion (1) and body portion (2) are held together by a clamping element (5) which can be seen to have deformed the sealing means (3) preferably by putting it under compression but which still allows the requisite movement between lid portion (1) and body portion (2). The clamping element (5) of the embodiment of Figure 1 acts on protrusions of the lid portion (1) and body portion (2), one of which portions carries the flap means (4). The clamp shown has the form of a dove-tail joint where the protrusions on the lid portion and body portion and the groove in the clamping element (5) may taper (for example into the papers drawn), in which case movement of the clamping element over the protrusions brings the lid and body portions together. The clamping arrangement of Figure 1 is not however necessary, and Figure 2A shows the invention in the absence of any particular clamping arrangement. Thus, a mechanical fastening between lid portion (1) and body portion (2) may be provided independently of and/separated from the flap means (4). Figure 2B shows an alternative employing a claim similar to that of Figure 1. Figure 3 shows a cable splice closure that may embody the invention. A sealing means (3) can be seen to run around a perimeter of a body portion (2) of the splice closure thereby forming a seal between body portion (2) and lid portion (1) when they are brought together by pivoting around hinge (10). A flap (4) will protection sealing means (3) against ingress of dirt for the like. Slots (6) may be provided into protrusions provided for engagement with clamping elements (5). Alternatively such slots (6) may be provided continuously along an edge of the body portion (2) for receipt of the flap means (4). A flap (4) may extend all around the perimeter of, for example, the lip portion (1) or separate flaps (4) and (11) may be provided at different parts of the perimeter. Other features of the cable splice closure are visible in Figure 3, for example, cable ports (7), cable gripping elements (8) and optical fibre organiser trays (9). The splice closure may however be designed for copper pairs or for coaxial cables, in which case it would contain, for example, means for organising or securing copper pairs or CATV splitter circuits. The hinge (10) as shown allows for merely pivotal motion between the lid portion (1) and body portion (2) but it may be designed to allow some translational motion between lid portion (1) and body portion (2), particularly at the last stages of closure of lid portion and body portion. This facilitates even pressure being applied all around the sealing means (3). It also facilitates provision of flap means along the hinged edges of the lid portion and body portion since sliding motion of a flap means over (for example) the body portion is thereby made easier. This translational movement between lid portion (1) and body portion (2) may be achieved using a hinge that comprises a pivot pin in the lid portion (or body portion) that is received in an elongate slot in the body portion (or lid portion). Such a slot preferably has a width substantially equal to the diameter of the pivot pin and has a length greater than that diameter extending substantially perpendicular to the plane at which the lid portion and body portions meet.

Claims: Claims 1. A closure for a cable joint, comprising a lid portion and a body portion arranged to be fastened together substantially to close the closure, sealing means for sealing the interior of the closure against ingress of moisture, wherein the sealing means is located between the lid portion and the body portion when the two portions are fastened together in use, and wherein the lid portion and/or the body portion is/are provided with flap means which when the two portions are fastened together in use is located to the exterior of the closure in relation to the sealing means and is arranged substantially to block ingress of dirt or the like between the lid and body portions while allowing some convergence and/or divergence of the lid and body portions when they are fastened together in use. 2. A closure as claimed in claim 1, wherein the flap means comprises a flap provided on the exterior of one of the portions of the closure, and is arranged to overlap part of the exterior of the other portion of the closure when the two portions are fastened together in use. 3. As closure as claim in claim 2, wherein the flap is provided on the lid portion of the closure. 4. A closure as claimed in any one of claims 1 to 3, wherein the lid portion and the body portion are hinged together. 5. A closure as claimed in any one of claims 1 to 4, which is provided with one or more clamping elements for fastening the lid portion and the body portion together. 6. A closure an claimed in any of claims 1-5, wherein the flap means of the lid portion or body portion is held in resilient bias against respectively the body portion or lid portion. 7. A closure as claimed in any of claims 1-6, wherein convergence and/or divergence of the lid portion and body portion causes relative motion that is predominantly sliding between the flap means and the lid portion or body portion.

Inventors: FREMGEN DIETER, FREMGEN, DIETER
Applicants: FREMGEN DIETER, RAYCHEM LTD, ROSE WALTER GMBH & CO KG, FREMGEN, DIETER, RAYCHEM LIMITED, WALTER ROSE GMBH & CO. KG
Application year: 1994
Main classification: H02G15
IPC codes: F16B2, H02G3, H02G15